I am getting back into flying after a few years off. I need new packs for my transmitters and receivers. All were NiCad. I can find replacement packs that are NiMh. My question is: Can I use the wall chargers that came with the transmitters to charge the packs or do I need a new charger.

I also have an ACE R/C charge master that can charge 3 receivers at 50ma, 1 at 120ma and 2 transmitters at 50ma. Can I use these or do I need new chargers?

I am getting back into flying after a few years off. I need new packs for my transmitters and receivers. All were NiCad. I can find replacement packs that are NiMh. My question is: Can I use the wall chargers that came with the transmitters to charge the packs or do I need a new charger.

I also have an ACE R/C charge master that can charge 3 receivers at 50ma, 1 at 120ma and 2 transmitters at 50ma. Can I use these or do I need new chargers?

How old is your radio system? If it's really old, with wide band transmitters, it may not be legal to use them. That is something like 30 years old or so.

The newer Nih cells usually have more milliampere hour capacity than the original Nicads. I've been using my wall chargers on the higher capacity Nihs cells for years without issue.

Normally, the wall chargers put out about 50 milliamperes or so. If your transmitter battery is 1500 Mah, that wall charger will require a charging time of 1500/50 or about 30 hours.

It's interesting, when I bought my Spektrum DX7 some 6 years ago, that is exactly what Spektrum did, a 1500 Mah transmitter battery with a 50 Milliampere wall charger.

My new Spektrum DX8 radio has the proper wall chargers for it.

As for receiver power, if you are flying electrics, IMHO the way to go is to use a switching power supply such as the Castle Creations 10 Amp uBEC for the receiver. This uBEC connects to the motor battery, while it's output connects directly to your receiver battery input. That eliminates the receiver battery.

Also many brushless ESC controllers such as the Castle Creations ICE series also have a switching power supply to feed battery power to your receiver and servos.

If you're running glow/gas engines, just about everyone in my club running these engines have gone to the LiFe batteries for receiver power. If your receiver/servos can handle a 5 cell Nih battery pack, these LiFe batteries are a direct drop in, with no voltage regulator required. These LiFe batteries work, and work very well for this purpose. For the larger models, there is no comparison between the four or five "AA" size Nih battery packs, and the LiFe batteries. Under high current loads the LiFe batteries hold up their voltage far better than any Nih cell ever will. (Yup, I've run many tests on each of them)

One more thing on the LiFe's they hold their charge for a VERY long time, like over 90% of capacity after sitting on the shelf for near a year. Plus with a quality balancing charger, they can be field topped off in 30 minutes if need be. (Yes they require a balancing charger.)

In answer to charging your radio gear .... yes of course you can use the original chargers - but it will be SLOOOOOOOOOW.

As Denny says - most older chargers are 50mA rate ... so lets take my packs in my modern radios : 2300mAh

2300 / 50 = 46 hours

BUT that does not allow for losses or back emf / resistance of packs to charge ... so you add anywhere from 25 - 40% to the charge time. Your old packs were probably 500 - 600mAh and your manual qwould have said 14hrs charge ? That's 10 hrs at rate + 40% to ensure full charge.

So now my charge time is 46 x 1.4 = 64 hrs

WOW ! ... but a least I can say one thing - no chance of over-charge !! It can stay connnected literally indefinitely at that rate.

Battery packs for most radios can be had from 3rd party businesses who specialise in building packs ... cheaper than factory OEM and often higher capacity ... Well worth it.

For better charging ... there are Peak Detect chargers out now that are far better for charging radio gear .... they ensure safe full charge and cut-off charge when they hit full. My Prolux will charge my Tx / Rx packs fully in less than 2hours from low level. But I only use such rates when packs are seriously depleted after a long weekends flying etc. Rest of time I use the old 50mA chargers to top-up.

I am sure someone is going to pop-up and advise to fit a LiPo battery ... my advise is don't unless you know what you are doing. They require a different regime and charger ... my opinion is keep it simple and stay with NiMH which can be safely looked after similar to your old packs using your existing chargers.

I am sure someone is going to pop-up and advise to fit a LiPo battery ... my advise is don't unless you know what you are doing. They require a different regime and charger ... my opinion is keep it simple and stay with NiMH which can be safely looked after similar to your old packs using your existing chargers.

Nigel

Yeah, agreed:
IMHO, putting a LiPo battery into a transmitter designed for a Nih battery is simply not worth the effort. It's got to be balanced, and if you forget to turn off your transmitter, your LiPo battery is toast.

My Spektrum DX8 transmitter is designed for both Nih and LiPo batteries, but it will be running the Nih batteries for a long while. They work and work well. (Not the same for the receiver battery though. A transmitter pulls the same current through out the flight. The receiver battery current drain can and will change by orders of magnitude during the flight. I've measured peak DC currents on my Giant Scale Big Stick at 14 AMPS. For 14 Amps, you'd better be using sub C Nih cells, or a LiFe or A123 receiver battery.)

Yes but there are issues, 3 main ones:
1. Warranty is void if lipo is not specified. Yes, most folks get away with it but some TX have fried the voltage regulator. Then you are out of luck.
2. You forget to turn the TX off > you run it dead > dead is bad for lipos. Sometimes recoverable, sometimes not, but always somewhat damaged. Now you have a damaged lipo in your TX. Well.....it's your TX, do what you want.
But everyone always DOES remember to turn off the TX, right?
3. Must open the TX to charger. Not a big deal but somewhat of a hassle. And, it you screw up a lipo charge here you can toast your TX.

fly
If you're going to learn to fly them, you have to learn to fix them.

Yes but there are issues, 2 main ones:
1. Warranty is void if lipo is not specified. Yes, most folks get away with it but some TX have fried the voltage regulator. They you are out of luck.
2. You forget to turn it off > you run it dead > dead is bad for lipos.
But everyone always DOES remember to turn off the TX, right?

#2 also super easy - My equipment (I use nice stuff) tells me when I have been a bonehead. One has auto shutoff (awesome), one has the alarm (vibe and beeper). On my old ones that don't have it - I use a battery that costs between 5-15 bucks. If I do that (have not in many years) I am out that amount.

You are still paying for 8 LSD AA's at $25-50 so I am still money ahead and it reminds me to be diligent and turn the TX off. I actually learned in the old days when leaving your system on could fry your RF deck - so I am pretty good about it.

AA's just seem like the dark ages to me. Mark my words in the next 5 years or so LiPo/LiFe will be the TX standard. Watch someone is going to come back to this thread in three years and make me eat crow. LOL!

I use the LiFe 2s packs for my larger planes exclusively - no more BEC's for me either. The future is great!

I use the LiFe 2s packs for my larger planes exclusively - no more BEC's for me either. The future is great!

Mike

My giant scale models use a Castle Creations 10 Amp uBEC for receiver power, along with a two cell A123 battery for backup power.

And, my models fixed up with the Castle Creations ICE series of ESC's also use the CC 10 Amp uBEC as backup power. The ICE and uBEC BEC's are isolated from each other with a pair of 10 Amp Shottky diodes.

If anyone is interested in how this was done, I've got wiring diagrams.

? My pack of 8 Grundigs are $10 over the local shop counter. Plus if a cell does go down - I can replace individual from same counter without any need to find LHS or order online or replace a whole pack as would be case with a LiPo.

One hour charging

My Prolux is not far behind based on I rarely deplete my packs past about 60% ... and that charges via the built in charge socket without any need to open Tx battery case etc.

Lighter TX

This is actually a non-starter with me as I don't like the lightness of modern radios. My 1980's JR Propo which I flew Display, Competition and various with is about 1.5x the weight of my 9X and I prefer that. I use a neckstrap but that's more fort making it nice to move hands as needed etc.

Super long capacities (2x AA's)

See above ... most people I see / read are using similar capacity LiPo as my NiMH ... so in fact I get more use as my NiMH will run further downm than an 80% mark of a LiPo

More run time

See previous ... Tx we are talking about.

I agree totally with ref to models and need for capacity but light weight. First thing I did to my RTF ME109 was convert from NiMh to LiPo ... But for TX ... so far I have never seen any real convincing argument for the change. My Grundigs go on the 50mA charger ready for action at any time ... being 50mA - I don't even have to check whether AA's are in need of charge. My Tx is always ready to go ... and even when I get hjome tmrw from my trip to Singapore ... while away I unplug my Chargers ... I know my TX's will be fine to go fly WITHOUT charging ...

$10 solution ... isn't that same price as the famous $10 LiPo solution that used to quoted from online ?

I'm with Mike, obviously we need to take care not to expose the Tx to a higher voltage than it was designed for but assuming you can get around that one then there are battery battery options than NiXx IMHO.

Modern tech does indeed nearly double battery capacity. for instance my Dx8 comes as standard with a 2000mAh battery. The LiPo upgrade option is 4000mAh, albeit at the LiPo is a little thicker but it fits in the same battery compartment.

Not only does the LiPo/LiFe last twice as long but it has virtually zero self discharge. Standard NiMh batteries have a very high self discharge rate. Even turned off they lose up to 20% within the first 24 hours and continue to discharge at a slower rate after that. This means that if you dont fly for a while you will often find your battry almost flat when you get chance to use it. ok you can now get low self discharge NiMh but they have even lower capacity and they cost much more.

Personally i also used to go through a few NiXx packs, they quite quickly lose capacity and a cell going down altogether is pretty common. And if you use soldered tab battery packs as required in most Tx's then replacing a single cell is impractical. I've actually got loads of NiMh batteries that I got for kids toys etc that I only got a few cycles out of, I just use 'throw away' AA and AAA calls these days.

It's a no-brainer as far as I'm concerned, NiMh has had it's day. You wouldn’t dream of using them in your phone or laptop so why are they still a good idea in a Tx?

.......Not only does the LiPo/LiFe last twice as long but it has virtually zero self discharge. Standard NiMh batteries have a very high self discharge rate. Even turned off they lose up to 20% within the first 24 hours and continue to discharge at a slower rate after that. This means that if you dont fly for a while you will often find your battry almost flat when you get chance to use it. ok you can now get low self discharge NiMh but they have even lower capacity and they cost much more.....

My Grundigs certainly do not mimic what you say here ... I can leave them for weeks and still have good charge in them ... LSD is common amongst AA's now - its just that some brands like to push the adverts trying to convince everyone they are the only ones. My AA's are 2300mAh ... that is not low capacity ...

.....if you use soldered tab battery packs as required in most Tx's then replacing a single cell is impractical

.... but actually more simple than you think - I've done it before ... just means you have to buy a Tabbed cell and have a high heat soldering iron.

I've actually got loads of NiMh batteries that I got for kids toys etc that I only got a few cycles out of...

Oh dear .. I have AA's. AAA's from years ago still powering clocks, remotes etc. And yes I've salvaged tabbed cells from packs - made up new packs fropm such etc.

It's a no-brainer as far as I'm concerned, NiMh has had it's day. You wouldn’t dream of using them in your phone or laptop so why are they still a good idea in a Tx?

I agree that they are on way out ... but certainly not had their day yet.

At $10 a set for my Tx (8 AA) ... I am spending less than I would if I used a LiPo ...

Nigel - you can certainly use what you wish but holding up old school NiMh or even newer LSD AA batteries still just makes me chuckle.

NOTHING I have purchased consumer electronic wise has used them in MANY MANY years - with maybe the notable exception of TV remote controls. So my Camera's, cell phones, cordless phones, Video cam, video games, tablets and laptops all come with lithium battery technology. My power tools ALSO made the switch! My last Dremel cordless uses LiIon cells, my last drill as well.

There is a reason consumer electronics have moved on - it is time for our TX manufactures and to grow up and do the same. Several have - Spektrum for example, my DX18 came with a nice large LiPo battery and built in charger. Now others need to join in.

I know this is a little off topic but I have not been able to find a forum that would be able to help. I need a seperate battery pack for my receivers and servos and needed to know both what size the seperate battery pack should be in terms of number of NimH cells and how many maH they should be if the main battery pack is a 4000 maH pack that will give me a flight time of 6 minutes, as well as how this would be set up. Thank you very much for any help you can provide

I know this is a little off topic but I have not been able to find a forum that would be able to help. I need a seperate battery pack for my receivers and servos and needed to know both what size the seperate battery pack should be in terms of number of NimH cells and how many maH they should be if the main battery pack is a 4000 maH pack that will give me a flight time of 6 minutes, as well as how this would be set up. Thank you very much for any help you can provide

Not at all, always best to ask questions BEFORE, not AFTER!

Most Electric models are equipped with what is called a BEC, or Battery Elimination Circuit. There are several types of BEC's, one of them is a "Linear" type BEC, the other is a switching power supply type of BEC.

IMHO, those linear type BEC's should be limited to those small foamies, and have no place in higher powered models including yours.

These switching power supply types of BEC's borrow power from your 4000 Mah pack, converting its DC voltage down to the 5.0 Volts DC required for your receiver and servos. A number of suppliers make them, I've been using the Castle Creations 10 Amp uBEC now for some 5 years. They have been flawless in operation.

These uBEC's are hard wired to the INPUT of your ESC, its black and white wires. The output of the uBEC is simply plugged into the battery input of your receiver. If your ESC has a BEC in it, that BEC should be disconnected by removing the red wire from the ESC's servo cable that goes to the receiver throttle connection.

That way, you don't have the extra weight of the receiver battery, along with the requirement to charge the receiver battery before every day of flying.

Castle Creations shows exactly how it's done in their literature. Nice thing about these uBEC's, as long as your motor has power, so will your receiver and its servos. And, should you run your motor battery to low, properly set up, the ESC will shut off power to your motor, leaving plenty of power to run your receiver and servos, up to and including landing.

If you're working with a giant scale model, perhaps with over 1500 Watts into the motor, IMHO it's a good idea to have primary/backup battery power to the receiver. There are a number of ways to do this. If interested, let me know, I've got several threads in www.wattflyer.com on this subject.

BTW, Switching power supplies are very common now days. Your computer likely has several of them. Most fast chargers for your battery operated power tools have them. Televisions have several of them. Computer printers, Washing machines, the list goes on and on.

I am actually working on a project and one of the requirements is a second battery for the receiver and servos. I am running 4 servos and it is a sport flyer style.

FYI it is NEVER a good idea to directly parallel connect two Nickel Hydride or the older Nicad types of batteries. They don't share load very well.

These dual batteries should be isolated from each other with a high current diode. One good type is what is known as a Shottky diode, a device with about 1/2 the voltage drop of a typical silicon diode. Www.digikey.com sells to anyone with a credit card. The Shottky diodes are around $2.00 each.

The attached drawing shows how it can be wired up. You might want to consider those A123 batteries, or the LiFe batteries that have similar chemistry. These type batteries have much greater high current potential than the older Nih type battery packs.

I know they do I wish I could use them but Nicad or Nimh are required. The project designer is ignorant and scared of fires I do believe

Ah ha
Let the project designer know that the A123 cells or LiFe cells do not, and can not catch fire. There is nothing inside these cells that can ignite, or burn. In fact, awhile back, I screwed up and severely overcharged a two cell A123 pack. The battery pack ruptured, sending black dust all over the place, but zero fire.

Youtube shows a video clip of someone driving a big nail right through a fully charged 2300 Mah A123 cell. Lots of smoke, but NO FIRE. Another video clip with the same setup shows a similar test on a LiPo battery. Instant fire.http://www.youtube.com/watch?v=rb_J2QQ0k-4

Last summer, a club member was flying his Bipe, way over safe flying speed. At full throttle about 30 feet off the ground, the whole elevator came off, and the model went straight into the ground. The 50 cc gas engine was busted in a half dozen pieces. We actually had to use a garden rake to sweep up what was left of the model. There was not one piece left larger than the palm of your hand. We found the elevator about 200 feet away.

The receiver's LiFe battery was completely bent in half, and was smoking from the dead short. But, NO FIRE. That battery was still working after it burned the short circuit clear.

Just about everyone in my club has gone to the LiFe or A123 cells for their receiver/servo power supply. I've conducted many tests on the Nih cells vs the LiFe/A123's. Some of these larger models pull a measured 14 AMPS, when all seven servos are actuated at the same time. I've measured these peak current directly with my Fluke 87V multimeter with its one millisecond peak hold function.

FYI it is NEVER a good idea to directly parallel connect two Nickel Hydride or the older Nicad types of batteries....

I may be mistaken but I think by "second battery" he means a single Rx pack. First battery being the main pack powering the motor. Is that right Nitro23?

As an example of size, my DX7 radio set came with four standard size digital servos and a 4.8 volt 1100 mAhr NiCd Rx pack. I will probably never use it in flight as it seems barely adequate but I use it on the bench all the time for setting up systems. There are lots of choices for Rx packs. Some of the major radio manufactures make them in different sizes and chemistries. There are also numerous retailers that put together custom packs with your choice of cells.

You need to choose the chemistry you want to use to narrow your choices. Number of cells and physical layout must then be considered for fitting into your project.

#2 also super easy - My equipment (I use nice stuff) tells me when I have been a bonehead. One has auto shutoff (awesome), one has the alarm (vibe and beeper). On my old ones that don't have it - I use a battery that costs between 5-15 bucks. If I do that (have not in many years) I am out that amount.

You are still paying for 8 LSD AA's at $25-50 so I am still money ahead and it reminds me to be diligent and turn the TX off. I actually learned in the old days when leaving your system on could fry your RF deck - so I am pretty good about it.

AA's just seem like the dark ages to me. Mark my words in the next 5 years or so LiPo/LiFe will be the TX standard. Watch someone is going to come back to this thread in three years and make me eat crow. LOL!

I use the LiFe 2s packs for my larger planes exclusively - no more BEC's for me either. The future is great!

Mike

I may have to try the life 9.9V batteries. The rechargeable nimh aren't bad, but they deteriorate after time. Their 2500 mah ratings are unrealistic also, and are probably no better than the battery that you listed, which probably holds charge better too. The performance from batch to batch does not seem consistent either.

The guys using 11.1V lipo sounds really risky, unless they charge only to 11.3V which gives a much less than full charge. I'm amazed at how many people have used them, some burning out power supplies and more.